Equine Herpes Myeloencephalopathy (EHM) Updates:

RELEASED: EHV-1 Quarantine in El Dorado County

September 4, 2020:  No additional cases have been reported, and the associated quarantine in El Dorado County has been released. 

August 28, 2020:  No additional cases have been reported. CDFA continues to monitor the situation.

August 21, 2020:  A 17-year-old Thoroughbred gelding in El Dorado County displaying fever and progressive neurologic signs has been confirmed positive for the neuropathogenic strain of Equine Herpesvirus-1 on August 21th, 2020.  The gelding was euthanized, and a quarantine has been issued for the home premises containing 10 other horses, with enhanced biosecurity measures and twice daily temperature monitoring implemented.  The gelding has had no recent travel or show history within the past 14 days.  No additional clinical cases have been identified, and there is no association between this case and the EHV-4 incident in Imperial County. CDFA will continue to monitor the situation.

RELEASED: EHV-4 Quarantine in Imperial County

August 27, 2020: The additional EHV-4 positive horse has had confirmatory negative testing and the associated quarantine in Imperial County has been released. 

August 20, 2020: No new cases have been reported. CDFA continues to monitor the situation. 

August 6, 2020: One additional horse on the index premises, a 17-year-old Quarter Horse mare, was confirmed positive for EHV-4 displaying fever only, no neurologic signs. CDFA continues to monitor the situation.

August 4, 2020:  A 1-year-old Quarter Horse filly in Imperial County displaying acute neurologic signs has been confirmed positive for EHV-4 on August 3th, 2020.  The filly was euthanized, and a quarantine has been issued for the home premises containing three other horses, with enhanced biosecurity measures and twice daily temperature monitoring implemented.  The filly attended an event in Riverside County on July 18 and 19th, and event management has been notified and show participants have been instructed to monitor their horse’s temperatures twice daily.  No additional clinical cases have been identified.  CDFA will continue to oversee the situation.

While the most common causative agent of equine herpesviral encephalomyopathy is EHV-1, EHV-4 can rarely be associated with neurologic manifestations as well as respiratory disease.  As no alternative etiology could be definitively identified as the cause of the filly’s neurologic issues, this case is being classified as a suspect EHM.

RELEASED: EHV-1 Quarantine in Sonoma County

April 21, 2020: The index positive horse has met testing requirements for release with two (2) negative tests seven (7) days apart. There were no additional cases on the home premise so the associated quarantine in Sonoma County has been released.

April 15, 2020: No additional cases have been confirmed. CDFA continues to monitor the situation.

April 9, 2020: A 10-year-old Warmblood mare displaying neurologic signs has been confirmed positive for Equine Herpesvirus-1. The mare is quarantined and isolated at a referral hospital where she is receiving care. The Sonoma County home premises containing 48 horses is quarantined with enhanced biosecurity measures and twice daily temperature monitoring of all horses. CDFA will continue to oversee the situation. There is no link between this premises and the currrent EHV-1 quarantine premises in Alameda county.

RELEASED: EHV-1 Quarantine in Alameda County

May 12, 2020: All positive horses have had two negative tests seven days apart and the asssociated quarantine in Alameda County has been released. 

May 5, 2020: No new cases have been reported. The quarantine will be released when all positive horses have had two negative tests seven days apart.  CDFA continues to monitor the situation. 

April 27, 2020: No new cases have been reported. CDFA continues to monitor the situation.

April 22, 2020: No new cases have been reported. CDFA continues to monitor the situation.

April 18, 2020: Two additional horses, a 15-year-old pony gelding and a 20-year-old draft cross mare, displaying fever only, no neurological signs, have been confirmed positive for EHV-1. The horses have been isolated with additional biosecurity measures put in place. CDFA continues to monitor the situation.

April 15, 2020: One additional horse, a 24-year-old Thoroughbred mare, displaying fever only, no neurological signs, has been confirmed positive for EHV-1. The horse has been isolated with additional biosecurity measures put in place. CDFA continues to monitor the situation.

April 13, 2020: Four additional horses, displaying fever only, no neurological signs, have been confirmed positive for EHV-1, a 14-year-old Morab gelding, a 9-year-old Warmblood gelding, a 19-year-old Paint mare, and a 20-year-old Quarter Horse gelding. The limited supply of PPE and disinfectant, due to the COVID-19 situation, has made implementation of appropriate biosecurity to prevent the spread of infection a challenge. The facility management continues to take temperatures twice daily and isolate positive horses. CDFA continues to monitor the situation.

April 6, 2020: One additional horse, a 15-year-old pony gelding, displaying fever but no neurological signs, has been confirmed positive for EHV-1. The horse has been isolated with additional biosecurity measures put in place. CDFA continues to monitor the situation

March 31, 2020: One additional horse, a 15-year-old Warmblood gelding, displaying fever but no neurological signs, has been confirmed positive for EHV-1. The horse has been isolated with additional biosecurity measures put in place. The index mare has tested negative twice seven days apart and has been released from her individual quarantine. CDFA continues to monitor the situation.

March 27, 2020: One additional horse, an 18-year-old Quarter Horse gelding, displaying fever but no neurological signs, has been confirmed positive for EHV-1. The horse has been isolated with additional biosecurity measures put in place. CDFA continues to monitor the situation.

March 23, 2020: No new cases have been reported. CDFA continues to monitor the situation.

March 18, 2020: No new cases or compatible clinical signs have been reported. CDFA was onsite to assess biosecurity and continues to monitor the situation.

March 16, 2020: A 14-year-old pony mare in Alameda County displaying neurologic signs has been confirmed positive for Equine Herpesvirus-1. The mare has been isolated and quarantined at a veterinary hospital.  Forty-four (44) exposed horses on the home premise have been quarantined with enhanced biosecurity measures including twice daily temperature monitoring. CDFA was onsite March 14 to evaluate the situation. All potentially exposed horses have been traced and contacted. Any horse displaying clinical signs or a temperature over 101.5F shall be reported to the veterinarian for evaluation and potential nasal swab and blood sampling. CDFA continues to monitor the situation.

Quarantine RELEASED: EHV-1 Quarantine in Santa Barbara County

February 5, 2020: All positive horses on the quarantined premise have had two (2) negative tests seven (7) days apart. The quarantine has been released. There are no EHV quarantines currently in the state of California.

January 28, 2020: The two exposed horses on the premises have both received their first negative test.  Once an additional negative test is obtained at least seven (7) days apart, the horses and the premises will be released from quarantine. CDFA continues to monitor the situation.

January 22, 2020: An exposed horse on the quarantined Santa Barbara premise has been confirmed positive for Equine Herpesvirus-1. The aged miniature horse gelding displayed a fever and is recovering. CDFA continues to monitor the situation.

January 17, 2020: An exposed horse on the quarantined Santa Barbara premise has been confirmed positive for Equine Herpesvirus-1. The 6-year-old Quarter Horse mare displayed mild neurologic signs and is recovering. CDFA continues to monitor the situation.

January 10, 2020: A 21-year-old Quarter Horse gelding in Santa Barbara County displaying neurologic signs and fever has been confirmed positive for Equine Herpesvirus-1. On January 9, 2020 the gelding was euthanized due to severity of signs. The index premises with two remaining horses has been quarantined with requirements for enhanced biosecurity measures including twice daily temperature monitoring. There has been no recent movement of horses on or off the property. CDFA will continue to monitor the situation.